Union membership was about 15% in the 1930's and peaked at about 35% in the 1950's in the U.S. Currently, union membership is about 10%, even though in the past couple of decades, public sector union membership has increased.

Unions, labor movements and workers had specialty newspapers throughout the country. Some of these have been digitized and the links by state are below. Please note that I have excluded subscription databases from the list.
​(Updated October, 2018; recently added links are in BOLD)